Most electronic devices that incorporate audio recording capabilities, such as smartphones, personal computers, voice recorders, and the like, are designed to leverage audio recording for tasks that require only a relatively short amount of audio to be captured and stored at a time (e.g., on the order of seconds, minutes, or hours). For example, a smartphone may capture and store a few seconds of audio in order to interpret a voice command uttered by a user, or a voice recorder may capture and store an hour of audio in order to document what was spoken by participants in a meeting. This is because, historically, recording audio required a large amount of storage space per time unit, and thus it was not possible (or economically infeasible) to capture and store more than several hours worth of audio for extended periods of time, either locally on the device or at a remote storage location.
With recent advances in audio compression algorithms and increases in the density of storage devices, it is now possible to record audio over much longer timescales. For example, the open source Speex audio codec allows 16 kilohertz (kHz) monaural audio to be recorded at roughly 1.2 kilobytes (kB) per second, which equates to 4.2 megabytes (MB) for a full day's worth of recording, or 36 gigabytes (GB) for a full year's worth of recording. These storage sizes are quite reasonable in view of the capacities of modern storage devices. Accordingly, it would desirable to have techniques that can leverage long-term recordings of audio data for various purposes.